1. Field of the Invention
The present invention generally relates to trailer hitches of the type commonly used to connect a tractor vehicle to a trailered apparatus and, more particularly, to a hitch assembly which permits continuous adjustment of the elevation of the site of coupling of a hitch ball with an interactive socket mechanism.
2. Description of the Prior Art
Trailer hitches are devices that connect a tractor vehicle (also called a tow vehicle) to a trailer vehicle by means of a ball hitch which is mounted onto the vehicle, or mounted onto a tow bar which is connected to the vehicle. The hitch ball then mates with a socket located on the trailer tongue. This ball and socket configuration is designed to allow adequate rotation of the socket with respect to the ball so that the vehicle-trailer combination can maneuver around corners. Typically the socket mechanism has a releasably lockable coupling so that it locks onto the ball hitch to prevent decoupling while towing.
A common problem with hitches is that the ball and interactive socket of the tractor and trailered members are generally not at the same elevation to permit proper coupling. Accordingly, hitches have been disclosed having means for adjusting the elevation of the ball to accommodate the socket. Such modified hitches are described in U.S. Pat. Nos. 3,554,578; 4,103,928 and 6,663,133 which employ rotatable screw drive means to move the hitch ball in a straight vertical path. Said adjustable hitches are effective in the coupling of a tractor vehicle to an ordinary towed vehicle wherein the elevation of the ball must remain fixed in the course of the towing operation.
U.S. patent application Ser. No. 11/122,904, filed May 6, 2005 by J. R. Bartlett describes a trailered earth-moving apparatus adapted to be drawn by a small vehicle such as an all-terrain vehicle (ATV). The functioning of the earth-moving apparatus in digging, dumping and grading operations is controlled in part by the elevational positioning of the tongue of the trailered apparatus, said action causing tilting of the apparatus and consequent adjustable interaction with the underlying earth. In order to be effective, the tilting of the apparatus must be controlled in a continuous manner during forward motion of the coupled ATV and earth-moving apparatus. Other kinds of trailered working equipment such as a rake, rototiller, plow, aerator, cultivator, disc harrow, weed cutter and seeder can also be controlled by tilting effect. Such necessary tilting control is not achievable with adjustable hitch mechanisms of the prior art.
It is accordingly an object of the present invention to provide a hitch device for a trailered apparatus, said hitch device capable of providing continuous vertical adjustment during movement of said apparatus.
It is a further object of this invention to provide a hitch device as in the foregoing object amenable to easy coupling between a tractor vehicle and said trailered apparatus.
It is another object of the present invention to provide a hitch device of the aforesaid nature which, by virtue of said vertical adjustment, causes controlled tilting of said trailered apparatus in a vertical plane.
It is a still further object of this invention to provide a hitch device of the aforesaid nature mountable upon said tractor vehicle.
These objects and other objects and advantages of the invention will be apparent from the following description.